U.S. Pat. No. 4,206,799 which issued Jun. 10, 1980 to McDonald discloses a die casting machine having a stationary die half and an ejector holder block with an ejection box mounted one behind the other for movement toward and away from the stationary die half. There is a lost motion connection between the ejection box and the ejector holder block. Die core pieces are slidably received in the ejector holder block at an acute angle to the direction of movement of the holder block. Cylinders may extend the die core pieces toward the stationary die half. A hydraulic cylinder may push the ejection box toward the stationary die half after the die core pieces have been moved to their extended position. Once the ejection box is pushed into abutment with the ejector holder block, further movement of the ejecting box will push the ejector holder block along with the ejection box. In this way, the ejector holder block is moved into abutment with the stationary die half thereby forming a die cavity between the stationary die half and ejector holder block. The abutment of the ejection box with the ejector holder block provides an abutment for the rearward end of the die core pieces to lock these in their extended position. When the ejection box is moved away from the stationary die half, initially the ejector holder block remains stationary due to the lost motion connection. However, once the extremity of the lost motion connection is reached, further movement of the ejection box away from the ejector holder block causes the ejector holder block to move with the ejection box. The separation between the ejector holder block and the ejection box allows withdrawal of the die core pieces.
The tolerances of products cast with the die cast machine of this patent may be greater than desirable.
This invention seeks to overcome drawbacks of known die casting machines.